ATM network system

1. An ATM network system having a clock synchronization source and a plurality of nodes synchronized with said clock synchronization source, and set a plurality of routes for supplying a clock from said clock synchronization source to each of said nodes, wherein each of said nodes has a connection that is used to confirm whether a route for receiving the clock is normal or not, when one of said nodes detects a failure which occurred in a presently used route,said detecting node gives a failure signal to an other node to be supplied the clock from said detecting node itself through the failure-detected route, via the connection, and changes said failure-detected route under use into an other route, and when received the failure signal from said other node via the connection, changes said failure-detected route into an other route in accordance with the failure signal.

2. An ATM network system as claimed in claim 1 , wherein each of said nodes, when changing a route by a receipt of the failure signal, selects a route that the node is not received the clock from the node detecting said failure-detected route among said a plurality of routes.

3. An ATM network system as claimed in claim 1 , wherein each of said nodes, when having a different route set between the node and another node to be given the failure signal, the different route in a same direction with said failure-detected route, also sends out the failure signal to a connection corresponding to the different route.

4. An ATM network system as claimed in claim 1 , wherein each of said nodes having a plurality of ports inputed a clock which is outputted from any one of said clock synchronization source and other nodes; and wherein each of said nodes changes a route by change of a setting of each of said ports.

5. A clock supply route changing method for an ATM network system having a clock synchronization source and a plurality of nodes synchronized with said clock synchronization source, and set a plurality of routes for supplying a clock from said clock synchronization source to each of said nodes, wherein each of said nodes has a connection that is used to confirm whether a route for receiving the clock is normal or not, when one of said nodes detects a failure which occurred in a presently used route, said detecting node gives a failure signal to an other node receiving the clock from said dectecting node itself through the failure-detected route, via the connection, and changes the failure-detected route under use into an other route, and when received a failure signal via the connection, changes said failure-detected route into an other route in accordance with the failure signal.

6. A clock supply route changing method as claimed in claim 5 , wherein each of said nodes, when changing a route by a receipt of said failure signal, selects a route that the node is not received a clock from the node detecting said failure-detected route among said a plurality of routes.

7. An clock supply route changing method as claimed in claim 5 , wherein each of said nodes, when having a different route set between the node and an other node to be given the failure signal, the different route in a same direction with said failure-detected route, also transmits said failure signal to a connection corresponding to the different route.

8. A clock supply route determining method in an ATM network system in which said ATM network system is constituted based upon a private network-to-network interface specification; a plurality of nodes are formed as a pier group; any one of the nodes within said pier group is set as a pier group leader; and said pier group leader is set as a clock synchronization source; wherein each of said nodes acquires data about shortest routes defined from the node to each of other nodes; said pier group leader determines shortest routes from the pier group leader to each of other nodes as clock supply routes based upon said data about the shortest routes as clock supply routes; each of the nodes other than said pier group leader determines shortest routes defined from the node up to said pier group leader as clock supply routes based on the data of said shortest routes; and each of the nodes has a connection that is used to confirm whether a clock supply route for receiving the clock is normal or not, when one of said nodes detects a failure which occurred in a presently used clock supply route, said detecting node gives a failure signal to an other node to be supplied the clock from said dectecting node itself through the failure-detected clock supply route, via the connection, and changes said failure-detected clock supply route under use into an other clock supply route, and when received the failure signal from said other node via the connection, changes said failure-detected clock supply route into an other clock supply route in accordance with the failure signal.

9. A clock supply route determining method as claimed in claim 8 , wherein: when said pier group leader has a failure, a newly pier group leader is determined among the nodes other than said pier group leader; the newly pier group leader determines shortest routes defined from the newly pier group leader to the nodes as lock supply routes based on the data of said shortest routes; and each of said nodes other than the newly pier group leader determines the shortest routes defined from the newly pier group leader to said node as clock supply routes based upon said data of the shortest routes.